How can it be 21 UTF-8 bytes of order only 5 characters?

After writing some basic code to count the number of characters in String

, I found one example where UTF-8 encoded output creates 21 bytes from a 5-character character String

.

Here's the output:

String ==¦ อภิชาติ ¦==
Code units 7
UTF8 Bytes 21
8859 Bytes 7
Characters 5

      

        
        
        
      

    

I understand that Java's internal representation char

is 2 bytes and there is a possibility that some characters may need two blocks of Unicode code to display them.

Since UTF-8 does not use at most 4 bytes per character, how long is byte[]

more than 20 possible for 5 characters String

?

Here's the source:

import java.io.UnsupportedEncodingException;

public class StringTest {

    public static void main(String[] args) {
        displayStringInfo("อภิชาติ");
    }

    public static void displayStringInfo(String s) {
        System.out.println("Code units " + s.length());     
        try {
            System.out.println("UTF8 Bytes " + s.getBytes("UTF-8").length);
        } catch (UnsupportedEncodingException e) { // not handled }
        System.out.println("Characters " + characterLength(s));
    }

    public static int characterLength(String s) {
        int count = 0;
        for(int i=0; i<s.length(); i++) {
            if(!isLeadingUnit(s.charAt(i)) && !isMark(s.charAt(i))) count++;
        }
        return count;
    }

    private static boolean isMark(char ch) {
        int type = Character.getType(ch);
        return (type == Character.NON_SPACING_MARK ||
               type == Character.ENCLOSING_MARK ||
               type == Character.COMBINING_SPACING_MARK);
    }

    private static boolean isLeadingUnit(char ch) {
        return Character.isHighSurrogate(ch);
    }
}